S&P 500: On a knife’s edge

Last Thursday was a so-called 90% down-day for American stock markets (and many other bourses also recorded downward dynamics). A 90% down-day is defined as a day when downside volume equals 90% or more of the total upside plus downside volume and points lost equal 90% or more of the total points gained plus points lost. The historical record show that 90% down-days do not usually occur as a single incident on the bottom day of an important decline, but typically on a number of occasions throughout a major decline. As far as the very short term is concerned, 90% down-days are often followed by two- to seven-day bounces.

The stock market is on a knife’s edge at the moment as seen in the chart below, showing the long-term trend of the S&P 500 Index (green line) together with a simple 12-month rate of change (ROC) indicator (red line). Although monthly indicators are of little help when it comes to market timing, they do come in handy for defining the primary trend. An ROC line below zero depicts bear trends as experienced in 1990, 1994, 2000 to 2003, and in 2007. And 2010? With the ROC delicately perched just above the zero line, the primary trend is still bullish, but barely so.

Regarding seasonality, I have done a short analysis of the historical pattern of monthly returns for the S&P 500 Index from 1950 to August 2010. The results are summarized in the graph below.

Source: Plexus Asset Management (based on data from I-Net Bridge).

As shown, the six-month period from May to October has historically been weaker than the period from November to April as seen in the average monthly return of 1.05% for the “good six months” compared with 0.25%% for the “bad six months”. Importantly, when considering individual months, September (-0.18%) and October (-0.19%) have historically been the only two negative months of the year. (A word of warning, though: one should take cognizance of seasonality but understand that it is not a stand-alone indicator and it is anybody’s guess whether a specific year will conform to the historical pattern.)

Where does this leave us at this juncture? Considering an array of indicators, we are somewhat in no-man’s land regarding whether the bull or bear will prevail, leaving me to maintain a defensive stance as we wait for Mr Market to show his hand.